TIGHAR

Amelia Earhart Search Forum => Join the search => Topic started by: Todd Attebery on August 27, 2009, 12:40:55 PM

Title: Radium on Instruments
Post by: Todd Attebery on August 27, 2009, 12:40:55 PM

The new forum is great.  I've been following the progress for years, but I've never made a post.

Maybe this ideas has already been explored but I'm wondering if the Electra would have had instruments with dials painted with radium ?  I believe this was common in the 1920's and 1930's.  If the Electra did have dials painted with Radium, would sea water quicklu destroy it ?   If not, could they still be detected with a Geiger counter from under water from some reasonable distance ?

LTM.

Title: Re: Radium on Instruments
Post by: Martin X. Moleski, SJ on August 27, 2009, 02:29:25 PM

Water tends to absorb the radiation.

This new and improved Geiger counter (http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA800522) can "reliably detect 50 milligrams of radium at 250 feet in air and at almost 6 feet under water."  So water reduces the range of the detector by a factor of 40. 

I doubt that any ROV that TIGHAR might use would be getting within 6 feet of every part of the reef face where the instrument panel may have come to rest.  I would give higher priority to the standard underwater search instruments: lights, cameras, sonar.

                 Marty

Title: Re: Radium on Instruments
Post by: Tim Collins on August 28, 2009, 07:02:58 AM

Quote from: moleski on August 27, 2009, 02:29:25 PM

So water reduces the range of the detector by a factor of 40. 

I should also think that a magnetometer would also be more effective.

t

Title: Re: Radium on Instruments
Post by: Martin X. Moleski, SJ on August 28, 2009, 10:02:36 AM

The SS Norwich City (http://tighar.org/wiki/Norwich_City) left in the neighborhood of 5600 tons of debris on and around the reef.

That's liable to generate a lot of false positives.

I suppose if there's room, power, and bandwidth on the ROV, it might not hurt to add a magnetometer.

There are only a few pieces of the aircraft that are likely to generate significant magnetometer readings (engines and landing gear).

Here's a $6000 underwater magnetometer rated to 130':

http://www.quantrosensing.com/ (http://www.quantrosensing.com/)

Here's a towed magnetometer from the same company:

http://www.quantrosensing.com/digital.htm (http://www.quantrosensing.com/digital.htm)

It's only good to 500'.

At EPAC, I think we were hoping to get gear that could go
down to 1000' at least.  TIGHAR won't know until it looks
how far stuff tends to slide downhill from wrecks on
the reef.

               Marty